Data on human papillomavirus (HPV) type distribution in invasive and pre-invasive cervical cancer is essential to predict the future impact of HPV16/18 vaccines and HPV-based screening tests. A meta-analyses of HPV type distribution in invasive cervical cancer (ICC) and high-grade squamous intraepithelial lesions (HSIL) identified a total of 14,595 and 7,094 cases, respectively. In ICC, HPV16 was the most common, and HPV18 the second most common, type in all continents. Combined HPV16/18 prevalence among ICC cases was slightly higher in Europe, North America and Australia (74-77%) than in Africa, Asia and South/Central America (65-70%). The next most common HPV types were the same in each continent, namely HPV31, 33, 35, 45, 52 and 58, although their relative importance differed somewhat by region. HPV18 was significantly more prevalent in adeno/adenosquamous carcinoma than in squamous cell carcinoma, with the reverse being true for HPV16, 31, 33, 52 and 58. Among HSIL cases, HPV16/18 prevalence was 52%. However, HPV 16, 18 and 45 were significantly under-represented, and other highrisk HPV types significantly over-represented in HSIL compared to ICC, suggesting differences in type-specific risks for progression. Data on HPV-typed ICC and HSIL cases were particularly scarce from large regions of Africa and Central Asia. ' 2007 Wiley-Liss, Inc.Key words: human papillomavirus; genotype; cervical cancer; highgrade squamous intraepithelial lesions; meta-analysis; epidemiology Data on human papillomavirus (HPV) type distribution in women with invasive cervical cancer (ICC) and its precursor lesions are essential to predict the potential worldwide impact of new prophylactic vaccines against HPV16/18, 1,2 as well as to determine priorities for the inclusion of HPV types in future HPV vaccines and HPV-based screening tests.A standardised pooled analysis of 3,607 ICC cases 3 and a wider meta-analysis of 10,058 ICC cases 4 both confirmed that a majority of worldwide ICC cases are associated with HPV16/18. They also suggested some geographical variation in the importance of specific HPV types, 3,4 although data were limited or missing from many regions in Africa and Asia.A further meta-analysis in 4,338 high-grade squamous intraepithelial lesions (HSIL) showed that the most common HPV types in HSIL were broadly similar, but not identical, to those in ICC. 5 The purpose of the present publication is to update previous meta-analyses of HPV type distribution in ICC and HSIL with studies published between January 2002 and January 2006, including many from previously under-studied regions, and to identify remaining worldwide epidemiological data gaps prior to HPV vaccine implementation. Material and methodsThe detailed methods used for this meta-analysis of type-specific HPV prevalence have been reported previously, and are similar for both ICC and HSIL. 4,5 In brief, Medline was employed to search for citations published from January 2002 to January 2006 using the following MeSH terms: ''cervical cancer'', ''cervical intraepit...

Incidence data on human papillomavirus (HPV) infection are limited, and risk factors for transmission are largely unknown. The authors followed 603 female university students in Washington State at 4-month intervals between 1990 and 2000. At each visit, a sexual and health questionnaire was completed and cervical and vulvovaginal samples were collected to detect HPV DNA. At 24 months, the cumulative incidence of first-time infection was 32.3% (95% confidence interval: 28.0, 37.1). Incidences calculated from time of new-partner acquisition were comparable for enrolled virgins and nonvirgins. Smoking, oral contraceptive use, and report of a new male sex partner--in particular, one known for less than 8 months before sex occurred or one reporting other partners--were predictive of incident infection. Always using male condoms with a new partner was not protective. Infection in virgins was rare, but any type of nonpenetrative sexual contact was associated with an increased risk. Detection of oral HPV was rare and was not associated with oral-penile contact. The data show that the incidence of HPV associated with acquisition of a new sex partner is high and that nonpenetrative sexual contact is a plausible route of transmission in virgins.

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Among newly sexually active women, consistent condom use by their partners appears to reduce the risk of cervical and vulvovaginal HPV infection.

Intraepithelial lesions are common early events among women with incident HPV infection, and the interval between incident HPV-16 or HPV-18 infection and biopsy-confirmed CIN grade 2-3 appears to be relatively short.

Genital HPV infection is common and multifocal in young men, and its incidence is higher than that reported for similar cohorts of young women. The high rates of HPV infection in men should be considered when strategies for the prevention of HPV infection in female adolescents and young women are being developed.

Large-scale epidemiologic studies have been invaluable for elaboration of the causal relationship between persistent detection of genital human papillomavirus (HPV) infection and the development of invasive cervical cancer. However, these studies provide limited data to adequately inform models of the individual-level natural history of HPV infection over the course of a lifetime, and particularly ignore the biological distinction between HPV-negative tests and lack of infection (i.e., the possibility of latent, undetectable HPV infection). Using data from more recent epidemiological studies, this review proposes an alternative model of the natural history of genital HPV across the life span. We argue that a more complete elucidation of the age-specific probabilities of the alternative transitions is highly relevant with the expanded use of HPV testing in cervical cancer screening. With routine HPV testing in cervical cancer screening, women commonly transition in and out of HPV detectability, raising concerns for the patient and the provider regarding the source of the positive test result, its prognosis, and effective strategies to prevent future recurrence. Alternative study designs and analytic frameworks are proposed to better understand the frequency and determinants of these transition pathways.

Background: Although the variant lineages of human papillomavirus (HPV) types 16 and 18 are well established, their individual associations with high-grade cervical intraepithelial neoplasia (CIN) have not been extensively evaluated. Methods: Study subjects were women participating in the Atypical Squamous Cells of Undetermined Significance/ Low-Grade Squamous Intraepithelial Lesion Triage Study who were positive for HPV16 or HPV18 at enrollment. These women were followed every 6 months for 2 years. Viral isolates from enrollment samples were characterized by DNA sequencing and classified as variant lineages. Results: Over a 2-year study period, CIN3 was histologically diagnosed in 291 of the 779 HPV16-positive women and 47 of the 275 HPV18-positive women. Among women without CIN2-3 at enrollment, the risk of subsequent CIN3 was 2.7-fold greater for those with HPV16 African-2 [95% confidence